The present invention relates to a corrosion resisting copper alloy and more particularly to a corrosion resistant copper alloy specially suitable for use with a heat exchanger and the invention also relates to heat exchangers using such an alloy. Such heat exchangers may be intended to be used under severe corrosive conditions and may, for example, be heat exchangers for heating cooling water for automobile engines or heat exchangers intended for industrial use.
In general, heat exchangers used for cooling water for use in connection with automobile engines, which are generally termed "radiators", are composed of a brass material which comprises 65 percent copper by weight and 35 percent zinc by weight. It is to be appreciated that when an automobile is in use the heat exchanger may be affected directly by harmful elements contained in exhaust gas emanating from the automobile, or other automobiles running on the same road, and also such a heat exchanger may be affected by salinity when the automobile is used near the sea shore, or when used on roads that have been treated with salt to prevent or minimize icing on the roads. Additionally the heat exchanger is always in contact with the heat exchanging medium circulating therein, and such a heat exchanging medium may be corrosive, particularly if the heat exchanging medium contains anti-freeze components. Thus heat exchangers of the type under the discussion are frequently used under severely corrosive conditions, with the heat exchanger being corrosively attacked both from the inside and from the outside.
A heat exchanger such as an automobile radiator operates by circulating a heat exchanging medium through a large number of tubes, and during the circulation of the heat exchanging medium heat is conducted to heat radiating fins which are in thermal contact with the tubes. Therefore, in order to ensure that there is sufficiently good heat conduction between the interior of the tubes and the fins it is preferred to make the tubes with walls that are as thin as possible. It is also preferable to make the heat exchanger as light as possible, again by making the walls of the tubes as thin as possible. Not only does this facilitate handling of the heat exchanger but also minimizes the amount of material used in making the heat exchanger, and this minimizes the costs of the materials utilized.
However, since a heat exchanger made of brass will corrode (by means of the so-called dezincifying corrosion) under the above mentioned severe corrosive conditions, there is a minimum practical thickness for the tube walls when the tubes are made of conventional brass and thus there is a minimum practical limit to the improvements of heat conductivity and the saving of material cost that can be effected by minimizing the thickness of the tube walls.